Hair straightener



FIG. 1 is a perspective view of a hair straightener showing my new design;

FIG. 2 is another perspective view thereof;

FIG. 3 is a front elevational view thereof;

FIG. 4 is a rear elevational view thereof;

FIG. 5 is a left side elevational view thereof;

FIG. 6 is a right side elevational view thereof;

FIG. 7 is a top plan view thereof;

FIG. 8 is a bottom plan view thereof; and,

FIG. 9 is a perspective view of the hair straightener where the hair straightener is in an open state.

The broken lines in the drawings depict portions of the hair straightener that form no part of the claimed design. 

CLAIM The ornamental design for a hair straightener, as shown and described. 